JPS6282810A - Television receiver channel selection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a channel selection device for a television receiver having an electronic tuner.

BACKGROUND OF THE INVENTION There are conventional televisions that have electronic tuners, but electronic tuning devices can be roughly divided into two types: direct input type, which inputs the channel of the station you want to receive directly, and one which inputs each channel from the end. There is a scanning method that performs scanning.

Conventional scanning-type tuning devices are equipped with a tuning voltage generator that continuously changes the output voltage to cause the tuner to scan, and the tuning voltage is increased so that the time required from the start to the end of scanning is constant. Or it was lowered.

In other words, scanning was performed at a constant speed regardless of whether broadcast waves were present or not.

Problems to be Solved by the Invention Currently, there are 12 television channels in VHF and 50 channels in UHF, so it takes time to scan all the channels.

The present invention has been made with attention to such problems, and the time required for scanning is shortened.

Means for Solving the Problems In order to solve the above problems, the present invention provides a logical product (hereinafter abbreviated as AND) circuit that inputs a synchronizing signal and a horizontal pulse, a smoothing circuit that smooths the output, and a smoothing circuit. A differentiating circuit for differentiating the output of the differentiating circuit, a switch, and a switching device operated by the output of the differentiating circuit are provided, and the operating state of the switch is ignored for a certain period of time by this switching device.

Operation With the above configuration, when the present invention receives broadcast radio waves, the operation of the scanning operation button is ignored for a certain period of time, and scanning is stopped for a certain period of time, so that even if scanning is performed at a high speed, it is easy to select a station.

Example Examples of the present invention will be described in detail below.

FIG. 1 shows a first embodiment of the present invention, where 1 is an AND circuit to which a synchronizing signal and a horizontal pulse are input, 2 is a smoothing circuit to which the output of AND circuit 1 is input, and 3 is a smoothing circuit 2. This is a differentiation circuit that differentiates the output.

Reference numeral 4 denotes a transistor, and the output of the differential circuit is inputted to the base, and a diode 5 is connected between the base of the transistor 4 and the ground in the opposite direction.

A tuning voltage generator 6 applies a tuning voltage to the tuner 7, and generates a voltage that continuously increases when the voltage at the terminal 8 is set to the ground level.

A resistor 9 is connected in series with the switch 10 and between the terminal 8 and ground.

]1 is a resistor connected between the power supply 12 and the collector of the transistor 4.

The channel selection device according to the first embodiment of the present invention has the above-described configuration. When selecting a channel, when the switch 10 is turned on, the tuning voltage generator 6 generates a continuously increasing voltage, and the tuner 7 Start scanning channels. At this time, when a broadcast radio wave is received, both the synchronization signal and the horizontal pulse are input to the AND circuit 1, so the AN
An output is obtained from the D circuit 1.

The output of the AND circuit 1 is smoothed by a smoothing circuit 2, and appears on the output side of the smoothing circuit 2 as a DC voltage. When this DC voltage is input to the differentiating circuit 3, the output of the differentiating circuit 3 becomes a positive pulse at the rise of the DC voltage and a negative pulse at the fall, but the negative pulse is shorted by the diode 5, and only the positive pulse is connected to the transistor 4. hangs on the base of.

Then, the transistor 4 is turned on and the voltage of the power supply 12 is applied to the terminal 8 of the tuning voltage generating means 6. Therefore, even if the switch 10 is ON, the voltage at the terminal 8 does not drop to the ground level while the pulse from the differentiating circuit 3 is applied, and the ON operation of the switch 10 is temporarily ignored and scanning is temporarily stopped.

In other words, when scanning channels with switch 10 turned on, if a broadcast signal is received, switch 1
Scanning is temporarily stopped even though 0 is turned on, and when the differential pulse of the differentiating circuit 3 disappears, scanning is started again if the switch 10 is kept on.

What is shown in FIG. 2 is a second embodiment of the present invention, and the same parts as in the first embodiment shown in FIG. 1 are given the same numbers and their explanations will be omitted.

Reference numeral 14 denotes a tuning voltage generator, which generates a voltage that increases step by step when a voltage is applied to the terminal 14.

15 is a load resistance of transistor 4, and switch 16
and in series with power supply 17.

The second embodiment of the present invention is constructed as described above, and its operation is the same as that of the first embodiment, so a description thereof will be omitted.

Effects of the Invention As described above, the present invention includes an AND circuit that inputs a synchronizing signal and a horizontal pulse, a smoothing circuit that smoothes the output thereof, a differentiating circuit that differentiates the output of the smoothing circuit, and a switching device that operates based on the output of the differentiating circuit. This switching device ignores the operating status for a certain period of time, and when a broadcast signal is received, the scanning operation stops for a certain period of time, making it easy to select a station even when scanning at high speed. That's what it is.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the first embodiment of the present invention, and FIG.
The figure is a block diagram of the second embodiment. 1...AND circuit 2...Smoothing circuit 3...Differential circuit 4...Transistor 6...Tuning voltage generator 7...Tuner 10.16 Switch 12.17...
·power supply

Claims (1)

[Claims] an AND circuit that inputs a synchronization signal and a horizontal pulse, a smoothing circuit that smoothes the output of the AND circuit, a differentiation circuit that differentiates the output of the smoothing circuit, a switch, a switch that generates a tuning voltage, and the switch. a tuning voltage generator that performs a scanning operation when the tuning voltage generator is operated; and a switching device that operates based on the output of the differentiating circuit and stops the scanning operation of the tuning voltage generator regardless of the operating state of the switch during operation. A channel selection device for a television receiver, characterized by the following.